Fall 2017 Great Tennessee Valley Outlook

[Windspeed]

Thanks, John, for letting us hijack your fall thread to talk winter.  Now, back to mid-range discussion.  Like Windspeed stated....looks like a tropical connection is possible late this weekend and into early next week depending upon your model preference.  I don't want to get my hopes up too much.  Looks like this will impact the eastern side of the forum area.

Concerned of the possibility of a high wind event occurring in the Southern Appalachians and Piedmont. The ECMWF races Nate rapidly from point of landfall to Labrador while transitioning the surface low with baroclinic forcing. Higher elevations could get hit hard especially if the surface low tracks further west. Even lower elevations could get in on the action. Aside from the wind event, 1-2" of rain is starting to look more likely even if the low misses East Tennessee to the east. Should be adequate moisture feed and enhanced lift due to Nate's interaction with the trough. Hopefully the high winds aren't strong enough to compromise trees and electrical infrastructure.

[Carvers Gap]

Great QBO discussion in the -NAO discussion on the main board.   We are just ahead of the curve this year w our discussions.  StormChaserChuck and UncleW have some good info looking at both sides of that coin.  Now, back to our regularly scheduled fall programming where we are hoping for rain.

[John1122]

I'm hoping for some rain in the short term, we're about to kick into burn season and while soil moisture will allow us to avoid the deep, hard to extinguish fires like last season, flash fires are almost as bad in this type weather. I'm pulling for Nate.

[jaxjagman]

No drought  in our area, which is good news to me.These tropical systems this year has been unreal for our area.

[Carvers Gap]

Looking like the entire forum area is now modeled to receive some rainfall late this weekend and into early next week.   Other than a few hundredths, this will be the first real rainfall for TRI since September 5th.

[Windspeed]

Looking like the entire forum area is now modeled to receive some rainfall late this weekend and into early next week.   Other than a few hundredths, this will be the first real rainfall for TRI since September 5th.

MRX:

Ahead of the storm making landfall on Sunday we will see precipitation chances increase as low level flow begins to turn southerly bringing in more moist air. Precipitation ahead of the tropical storm looks like it could start as early as Saturday morning, but we will have much better chances Saturday evening. Precipitation should continue as the tropical storm moves up the southeast towards our area. Latest National Hurricane Center forecast has the storm passing over our area Monday morning with it possibly still being a tropical depression. The latest ECMWF has shifted the path of the storm further west towards Louisiana to be more in line with the GFS. So over the weekend I have trended a bit more towards the GFS and it`s QPF amounts since it has been pretty consistent in it`s path of this system for several runs now. The main path of this storm and the location of the frontal boundary will likely be where we see the highest precipitation amounts over the weekend and into next week. Most models are keeping the main band of the heaviest rain off to our west...But we can`t rule out some heavy rain here if the track of the storm shifts or the front makes further eastward progress than we anticipated. Currently think we could see widespread precipitation amounts of 1-3 inches in our area, but it`s possible some places could see up to 4 or 5 inches. This rain will fall over several days and with our recently (very) dry conditions we`ve experienced the rivers and lakes should be able to handle a good amount of water. Wind speeds are tough with a system like this since they can really lose steam once they move inland into rougher terrain, but we could see winds of 20+ mph with higher gusts Sunday and Monday, especially in the higher terrain. Once this system finally exits the area we could see some lingering showers into the middle of the week, but dry conditions should return by Thursday as a high pressure system slides south of the area.

[Daniel Boone]

There's a disconnect going on within the forum area over the dryness variation within the area. The eastern valley area is much drier, deeper down as well. Carvers has pointed out how long it's been since substantial rainfall in the tri-cities area. That area as well as here didnt get the substantial amounts from harvey or irma as did western areas. It is dry and fire danger elevated in eastern forum sections.

[Carvers Gap]

Thanks, Flash.

Some Friday morning positives. Short, mid, and LR discussion....

1.  Looks like modeling is now in the camp of substantial rains fall coming to the forum area(especially from the Nashville eastward, from Saturday night into the middle of next week.  The MRX post above covers that pretty well.

2.  As Jeff correctly noted, November has a chance to be cool.  Well, behold the Euro Weeklies last night which bring seasonable weather to the eastern half of the country by week's 3-4...and then hold it there.  They even try to pop a sort-of  negative NAO during the second half of its 46 day run.  (I will have to see it to believe it.)  I say sort-of because heights build over the Davis Straits during week 4 and then move them to the North Atlantic just south of Greenland.  And that may seem like too much discussion for just a seasonable pattern...but sure beats what has been a locked-in, wall-to-wall ridge(for entire runs) during the last several model runs. The much debated -QBO  dropped from -14.42 to -15.28 for August and September, respectively.  That is interesting to see it level-off a bit.  One has to wonder if there is some sort of response there to the ENSO state.  I don't know.  But most -QBOs drop at a pretty good clip once they go negative.   Is this just a temporary plateau (which I suspect) before continuing its downward fall?  Stay tuned.  The 50mb (30mb numbers above) has a tendency to trail the 30mb flip by a few months.  It has now begun to fall as well.

3.  Lots of variables in play for this run of the Weeklies.  There are times the run gets a bit wonky early on, but the last half is a stable, strong western ridge at 500 that builds well into Alaska.   

4.  I still remain concerned that the Niña will move to moderate strength.  That growing cold pool around the equatorial eastern Pacific seems to have a chance to get stronger as colder water seems destined to reach the surface.  Winter still looks like an uphill slog...so enjoy seasonal temps when you can and hope for a weaker Niña.  The graphic below is from the October 3rd ENSO update.  Jax shared this earlier.

5.  (Edit) As a final thought...we have had some late season hurricanes/early Noreasters (resulted in very early snows here in E TN, especially the mountains) during the past ten years.  It seemed that those storms changed )what looked like a promising winter pattern) by shaking-up the wavelength pattern over NA.  They created enough instability that it took the winter pattern longer to settle in or it did not settle in at all.  With the LR pattern looking very warm, might it be some late season Tropical mischief that shakes-up the wavelengths just enough o prevent eastern ridging from building during the winter months?  Jeff's explanation is far more scientific and is a great post.

[John1122]

A few years ago I looked back over the last 100 years or so and found that a BN November was a very good indicator of a BN winter. Especially a BN Jan-Feb. Going by memory, and it may be a little faulty, but I believe it was close to 80 percent of years with a BN November produced a colder/snowy winter in the area. AN Novembers produced a similar rate of AN winters.

[jaxjagman]

NMME shows a weak to moderate Nina.SST's in the Gulf of Mexico  running well above normal.

[John1122]

Probably just the GFS being the GFS but it hints at some mountain top snow showers late in the run with highs in the 40s/50s in the lower elevations. October is normally our most extreme month temp wise. Can be very hot early month and very cold late month. It and April are generally the months where it is not uncommon to be in the mid 80s for days on end or it can snow during the month.

[Carvers Gap]

Weeklies have checked-in w/ AN temp for the next 46 days.  Will give a closer look tomorrow unless Jeff wants to give us his interpretation (edit...spell check is killing me) first.  

[nrgjeff]

Thanks for the props y'all. Just got back from the Blue Ridge. At least we had a couple nice days before the rain, lol! Since the weeklies are depressing, I will pivot to positive.

I think Tennessee will have a good leaves year after all. Highest elevations might be a little dull due to the cold, hot, Nate knuckle ball (worse than a curve ball). However I saw encouraging signs between 2,000 and 5,000 FT, esp the 3-4K sweet spot. Leaves are at or only slightly ahead of schedule. At lower elevations the early cold was not quite enough to trick the trees. Recent warmth really does not matter since trees start to shut down anyway based on the sun. Mid-mountain looks on schedule. I figure the October 14-21 window will offer its usual treats in the mountains esp at/below 4,000 FT. Mulling over the Cherohala in the next several days. Other options include waiting a couple weeks for state parks between 2,000 and 3,000 FT. From what I see, no concerns below 5K.

[EastKnox]

2 hours ago, nrgjeff said:

Thanks for the props y'all. Just got back from the Blue Ridge. At least we had a couple nice days before the rain, lol! Since the weeklies are depressing, I will pivot to positive.

I think Tennessee will have a good leaves year after all. Highest elevations might be a little dull due to the cold, hot, Nate knuckle ball (worse than a curve ball). However I saw encouraging signs between 2,000 and 5,000 FT, esp the 3-4K sweet spot. Leaves are at or only slightly ahead of schedule. At lower elevations the early cold was not quite enough to trick the trees. Recent warmth really does not matter since trees start to shut down anyway based on the sun. Mid-mountain looks on schedule. I figure the October 14-21 window will offer its usual treats in the mountains esp at/below 4,000 FT. Mulling over the Cherohala in the next several days. Other options include waiting a couple weeks for state parks between 2,000 and 3,000 FT. From what I see, no concerns below 5K.

I'm going backpacking near Gregory Bald Oct 19-22.  Our campsites are all between 3k and 5K feet.  It's looking like dry and cooler that weekend, so I'm looking forward to seeing the fall colors.

[jaxjagman]

Some of the seasonals show Nina peaking into winter then rising shortly after.Strong wind burst is showing up today around 3.4 maybe in a couple weeks ,though this could change.MJO has some strong signals by both the GEFS and Euro showing it in the Western Pacific.Sure hope the NMME is wrong for Nov.,one of our wettest months climo could potentially get robbed looking at it.

 

[nrgjeff]

Hopefully it is wrong. I cannot deal with another spring severe season tease-dud. 

In the short-term, hi-res models are atrocious since Nate left. They cannot decide how to handle 70 dews in October. Convection or crap-out? Errors have been bad both ways.

In the mid-term, both weekly products have a cool down right ahead of Halloween. Can we get a year without rain for the little ones?

This weather pattern is so hideous I almost miss the Political Roundtable. 

[Windspeed]

The mid-range keeps a chance of rain with a weakening frontal boundary moving through early next week. It's not much though. The pattern looks like a return to dry conditions for a while.

 

Short-term hires models still flirt with some weak storms in the eastern Valley this evening. As nrjeff alluded to, this may crap out. I see nothing on radar trying to get going yet.

 

[John1122]

It's going to go back to feeling like fall again next week, at least for a while. Probably see some 60s and low 40s in the area. Last Saturday night was as warm a night as we get in summer with the high dps and warm air pumping up from Nate. It was 79 at midnight with a dp in the low 70s. There should at least be dry air and upper 50s this weekend at night.

[jaxjagman]

Long range heading into the end of Oct into Nov seems dependent on if we have a typhoon recurving off of Japan or not.GFS and Euro are having a hard time where it's gonna go.The Euro yesterday had it going into Japan,now today it's back off shore.GFS today now shows it going into China.Something to keep a eye on

CPC has been down the last couple days and nothing is updating.MJO index has been stuck on Oct 10,plus no enso updates.But either way it doesn't look as progressive but still has some strong signals with a KW working east.Posted a graph.

Jamstec update looks warm in the Valley,DJF.weak Nina.More so better chance of winter,in the W/NW Valley.Plus ice and severe,the SST's in the GOM look warm.Like every other seasonal ,Nina should peak into winter and be short lived.But i'm still skeptical using Jamstec.They base the anamolies from 83"-06" for it's forecast.Wish they'd show by month and not tri-months.The NMME shows a potential active January along with some other seasonal models

[Carvers Gap]

Both the 0z Euro and GFS ensembles are showing the western ridge pattern returning in the mid-term, days 10-15.  If we flip to BN temps in late October...that is gonna hurt after these warm temps.

[Carvers Gap]

14 hours ago, jaxjagman said:

Long range heading into the end of Oct into Nov seems dependent on if we have a typhoon recurving off of Japan or not.GFS and Euro are having a hard time where it's gonna go.The Euro yesterday had it going into Japan,now today it's back off shore.GFS today now shows it going into China.Something to keep a eye on

CPC has been down the last couple days and nothing is updating.MJO index has been stuck on Oct 10,plus no enso updates.But either way it doesn't look as progressive but still has some strong signals with a KW working east.Posted a graph.

Jamstec update looks warm in the Valley,DJF.weak Nina.More so better chance of winter,in the W/NW Valley.Plus ice and severe,the SST's in the GOM look warm.Like every other seasonal ,Nina should peak into winter and be short lived.But i'm still skeptical using Jamstec.They base the anamolies from 83"-06" for it's forecast.Wish they'd show by month and not tri-months.The NMME shows a potential active January along with some other seasonal models

Great post, Jax.

[Daniel Boone]

You guys no doubt already know about the qbo/mjo correlation but, thought I would post a decent description limk in case some lurkers don't. This may be what keps us from having a run of the mill la nina winter. 

http://journals.ametsoc.org/doi/abs/10.1175/JCLI-D-16-0620.1

[nrgjeff]

Japan Met Agency and most of the models have it tracking toward Japan. Met Agency forecast ends 1/3 to 1/2 way toward Japan. It is only a TS now but they have it going to a Cat 3 at 100 knots, 115 mph. Major hurricane strength typhoon might impact the wx pattern. A weaker storm would have muted effect.

For now I can go with another strong cold front after late weekend warmth. Cool could last until Halloween. I would need another forcing mechanism to deviate from the return to warmth in early November shown on both weekly products. Right now we only have TS in the western Pacific.

UPDATE: Euro weekly charts are uninspiring and the CFS is probably too cold.

On the plus side the system early next week looks less robust, which should be a plus for fall leaves.

[John1122]

Looks like we get these few days below normal, bump up to AN for a few days then head cooler for the last week of the month and into early November. If we can pull a BN November that will bode well for winter for people who like cooler winters.

 

[Carvers Gap]

Euro Nino3.4 has trended less cool when comparing the September 1 and October 1 outlooks.  Dips much less into weaker territory.  Reference found in the Nina discussion(General Discission forum) by stormchaserchuck.   Though the western Pacific will get cooler before it warms rather quickly as modeled over the next six months.  Great disco and worth a read...link below

 

[nrgjeff]

CFS weeklies turned warmer after the Halloween chill. Figure the Euro weeklies will too on Thursday evening. All is not lost. A good cold front or two in October leaves the door open for at least some variability later in winter. Overall though it's hard to ignore the mild background.

Regarding the main weather discussion, May subsurface sometimes works. So does betting red or black at the casino. 

[Carvers Gap]

20 hours ago, nrgjeff said:

CFS weeklies turned warmer after the Halloween chill. Figure the Euro weeklies will too on Thursday evening. All is not lost. A good cold front or two in October leaves the door open for at least some variability later in winter. Overall though it's hard to ignore the mild background.

Regarding the main weather discussion, May subsurface sometimes works. So does betting red or black at the casino. 

Yeah, sorry....I should specify.  The La Niña discussion is what folks should look at...I don't even think I read the first post.   I think seasonal forecasting as a whole has plenty of similarities to Vegas, especially from the May time frame.  The last page of that thread is really good.  

I have noticed that the models will show wall-to-wall warmth at times only to miss some sharp cool downs.  But yeah, the mild background is there.  Maybe some of these typhoons can shake-up the pattern.  Leaves here at the lower elevations have slowed changing a bit in changing w these warm mornings.  While they definitely change w the decrease in daylight, cold mornings can move the along more quickly.  

[Windspeed]

This weekend looks unseasonably warm into Monday with highs in the upper 70s. Might even break 80 on Sat and Sun. Next week looks like our first real cooldown however. Both majors are breaking off upper level energy over the southern Mississippi Valley. As that advances, a decent surface low develops over the Gulf or southern Tennessee Valley and rides northeast along the frontal boundary. A strong trough digs behind. Should really get us to seasonal averages with highs upper 50s / low 60s. Is that 30s I spy for lows? We may even get our first frost Wed/Thur in upper eastern portions of the Tennessee Valley! Woohoo! And perhaps even a normal cool Halloween?

[Carvers Gap]

10.19.17 Weeklies Update

The Weeklies were not as warm as I expected.  They reach into the first few weeks of early December...long way off, but those were the only warm weeks outside of week one.  The control was snowy for NE TN...I discount that at this point .  It absolutely buried NE TN.  The mean had a couple of climo inches north of I-40 from Nashville eastward.  The first 32 days of the Weeklies were BN to normal for the forum area.  The southern reaches of the forum area in northern MS and AL were most BN.  For those new to the forum this season...the Weeklies are a 46 day forecast based upon the 0z Euro if I remember correctly.  I expected a much warmer pattern.  Cold was centered over Arklatex region. New England was much above normal for temps for both the 32 and 46 day timeframes.  I will update this post later as more of the run data becomes available.  

[jaxjagman]

CPC Seasonals are out today as well as the IMME.

http://www.cpc.ncep.noaa.gov/products/predictions/long_range/fxus05.html

 

IMME shows the Valley dry like the NMME in Nov.DJF  looks to be 0.5-1.0 "AN", temp2m.Not totally dry anyways.